Seasonal Relationship between Net Primary and Net Community Production in the Subtropical Gyres: Insights from Satellite and Argo Profiling Float Measurements

Abstract. Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP) and calcification (NCC). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in the seawater aragonite saturation state (Ωa). Results of flume studies using intact reef habitats (1.2 m by 0.4 m), showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm) and high flow (35 compared to 8 cm s−1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h−1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from benthic communities with four different compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water-residence times in neighbouring areas dominated by turfs, macroalgae and carbonate sand.

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Seasonal patterns in Arctic planktonic metabolism (Fram Strait – Svalbard region)

Biogeosciences ◽

10.5194/bg-10-1451-2013 ◽

2013 ◽

Vol 10 (3) ◽

pp. 1451-1469 ◽

Cited By ~ 24

Author(s):

R. Vaquer-Sunyer ◽

C. M. Duarte ◽

J. Holding ◽

A. Regaudie-de-Gioux ◽

L. S. García-Corral ◽

...

Keyword(s):

Arctic Ocean ◽

Early Spring ◽

The Arctic ◽

Fram Strait ◽

Metabolic Rates ◽

Net Community Production ◽

Western Sector ◽

The Arctic Ocean ◽

European Arctic ◽

Community Production

Abstract. The metabolism of the Arctic Ocean is marked by extremely pronounced seasonality and spatial heterogeneity associated with light conditions, ice cover, water masses and nutrient availability. Here we report the marine planktonic metabolic rates (net community production, gross primary production and community respiration) along three different seasons of the year, for a total of eight cruises along the western sector of the European Arctic (Fram Strait – Svalbard region) in the Arctic Ocean margin: one at the end of 2006 (fall/winter), two in 2007 (early spring and summer), two in 2008 (early spring and summer), one in 2009 (late spring–early summer), one in 2010 (spring) and one in 2011 (spring). The results show that the metabolism of the western sector of the European Arctic varies throughout the year, depending mostly on the stage of bloom and water temperature. Here we report metabolic rates for the different periods, including the spring bloom, summer and the dark period, increasing considerably the empirical basis of metabolic rates in the Arctic Ocean, and especially in the European Arctic corridor. Additionally, a rough annual metabolic estimate for this area of the Arctic Ocean was calculated, resulting in a net community production of 108 g C m−2 yr−1.

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Neural network-based estimates of Southern Ocean net community production from in situ O<sub>2</sub> / Ar and satellite observation: a methodological study

Biogeosciences ◽

10.5194/bg-11-3279-2014 ◽

2014 ◽

Vol 11 (12) ◽

pp. 3279-3297 ◽

Cited By ~ 7

Author(s):

C.-H. Chang ◽

N. C. Johnson ◽

N. Cassar

Keyword(s):

Neural Network ◽

Organic Carbon ◽

Southern Ocean ◽

Mixed Layer ◽

Sea Surface ◽

Carbon Export ◽

Net Community Production ◽

Basin Scale ◽

Community Production

Abstract. Southern Ocean organic carbon export plays an important role in the global carbon cycle, yet its basin-scale climatology and variability are uncertain due to limited coverage of in situ observations. In this study, a neural network approach based on the self-organizing map (SOM) is adopted to construct weekly gridded (1° × 1°) maps of organic carbon export for the Southern Ocean from 1998 to 2009. The SOM is trained with in situ measurements of O2 / Ar-derived net community production (NCP) that are tightly linked to the carbon export in the mixed layer on timescales of one to two weeks and with six potential NCP predictors: photosynthetically available radiation (PAR), particulate organic carbon (POC), chlorophyll (Chl), sea surface temperature (SST), sea surface height (SSH), and mixed layer depth (MLD). This nonparametric approach is based entirely on the observed statistical relationships between NCP and the predictors and, therefore, is strongly constrained by observations. A thorough cross-validation yields three retained NCP predictors, Chl, PAR, and MLD. Our constructed NCP is further validated by good agreement with previously published, independent in situ derived NCP of weekly or longer temporal resolution through real-time and climatological comparisons at various sampling sites. The resulting November–March NCP climatology reveals a pronounced zonal band of high NCP roughly following the Subtropical Front in the Atlantic, Indian, and western Pacific sectors, and turns southeastward shortly after the dateline. Other regions of elevated NCP include the upwelling zones off Chile and Namibia, the Patagonian Shelf, the Antarctic coast, and areas surrounding the Islands of Kerguelen, South Georgia, and Crozet. This basin-scale NCP climatology closely resembles that of the satellite POC field and observed air–sea CO2 flux. The long-term mean area-integrated NCP south of 50° S from our dataset, 17.9 mmol C m−2 d−1, falls within the range of 8.3 to 24 mmol C m−2 d−1 from other model estimates. A broad agreement is found in the basin-wide NCP climatology among various models but with significant spatial variations, particularly in the Patagonian Shelf. Our approach provides a comprehensive view of the Southern Ocean NCP climatology and a potential opportunity to further investigate interannual and intraseasonal variability.

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Net community production in the bottom of first-year sea ice over the Arctic spring bloom

Geophysical Research Letters ◽

10.1002/2017gl074602 ◽

2017 ◽

Vol 44 (17) ◽

pp. 8971-8978 ◽

Cited By ~ 8

Author(s):

K. Campbell ◽

C. J. Mundy ◽

M. Gosselin ◽

J. C. Landy ◽

A. Delaforge ◽

...

Keyword(s):

Sea Ice ◽

Spring Bloom ◽

The Arctic ◽

First Year ◽

Net Community Production ◽

Community Production

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Rates and drivers of Red Sea plankton community metabolism

10.5194/bg-2018-487 ◽

2018 ◽

Author(s):

Daffne C. López-Sandoval ◽

Katherine Rowe ◽

Paloma Carillo-de-Albonoz ◽

Carlos M. Duarte ◽

Susana Agusti

Keyword(s):

Red Sea ◽

Gross Primary Production ◽

Environmental Drivers ◽

Community Respiration ◽

Net Community Production ◽

Chl A ◽

Warm Environment ◽

Increasing Temperature ◽

Community Production ◽

Planktonic Communities

Abstract. Resolving the environmental drivers shaping planktonic communities is fundamental to understanding their variability, present and future, across the ocean. More specifically, resolving the temperature-dependence of planktonic communities in low productive waters is essential to predict the response of marine ecosystems to warming scenarios, as ocean warming leads to oligotrophication of the subtropical ocean. Here we quantified plankton metabolic rates along the Red Sea, a unique oligotrophic and warm environment, and analysed the drivers that regulate gross primary production (GPP), community respiration (CR) and the net community production (NCP). The study was conducted on six oceanographic surveys following a north-south transect along Saudi Arabian coasts. Our findings revealed that Chl-a specific GPP and CR rates increased with increasing temperature (R2 = 0.41 and 0.19, respectively, P

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Benthic buffers and boosters of ocean acidification on coral reefs

Biogeosciences Discussions ◽

10.5194/bgd-10-1831-2013 ◽

2013 ◽

Vol 10 (2) ◽

pp. 1831-1865 ◽

Cited By ~ 6

Author(s):

K. R. N. Anthony ◽

G. Diaz-Pulido ◽

N. Verlinden ◽

B. Tilbrook ◽

A. J. Andersson

Keyword(s):

Ocean Acidification ◽

Time Of Day ◽

High Flow ◽

Net Community Production ◽

Reef Environment ◽

Saturation State ◽

Low Co2 ◽

Coral Reef Environment ◽

Co2 Level ◽

Community Production

Abstract. Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (pn) and calcification (gn). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in seawater aragonite saturation state (Ωa). Results of flume studies showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm) and high flow (35 compared to 8 cm s−1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h−1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from four different benthic compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water residence times in neighbouring areas dominated by turfs, macroalgae and potentially sand.

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